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Kubernetes Pod YAML模版文件格式

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YAML

YAML 是专门用来写配置文件的语言，非常简洁和强大，远比 JSON 格式方便。它实质上是一种通用的数据串行化格式。

支持的三种数据结构：

  • 对象：键值对的集合，又称为映射（mapping）/ 哈希（hashes） / 字典（dictionary）
  • 数组：一组按次序排列的值，又称为序列（sequence） / 列表（list）
  • 纯量（scalars）：单个的、不可再分的值

YAML规则

  • 大小写敏感
  • 使用缩进表示层级关系
  • 缩进时不允许使用Tab键，只允许使用空格。
  • 缩进的空格数目不重要，只要相同层级的元素左侧对齐即可

数据结构

对象

key:value的键值对，使用冒号表示

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username: roddy
password: "ccccccc"

转成json

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{
  "username": "roddy",
  "password": "ccccccc"
}

数组

以横线“-”开头的行

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- Python
- Golang
- JAVA

转成json

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[
  "Python",
  "Golang",
  "JAVA"
]

复合结构

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username: roddy
password: "passwd"
server_ip:
    - 192.168.1.1
    - 192.168.2.2
    - 192.168.2.3
server_type:
    web: "nginx"
    db: "mysql"

转成json

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{
  "username": "roddy",
  "password": "passwd",
  "server_ip": [
    "192.168.1.1",
    "192.168.2.2",
    "192.168.2.3"
  ],
  "server_type": {
    "web": "nginx",
    "db": "mysql"
  }
}

参见yaml样例

推荐个在线yaml转json的网站：https://www.json2yaml.com/convert-yaml-to-json

YAML格式：

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name:
  - xiaomi
  - huawei
yaml:
  - slim and flexible
  - better for configuration
object:
	key: value
  array:
    - null_value:
    - boolean: true
    - integer: 1

转成JSON格式

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{
  "name": [
    "xiaomi",
    "huawei"
  ],
  "yaml": [
    "slim and flexible",
    "better for configuration"
  ],
  "object": {
    "key": "value",
    "array": [
      {
        "null_value": null
      },
      {
        "boolean": true
      },
      {
        "integer": 1
      }
    ]
  }
}

YAML创建Pod

Kubernetes 资源是通过声明的方式创建的，因此可以使用 YAML 文件。Kubernetes 资源（比如 Pod、服务和部署）是使用 YAML 文件创建的。后期我们会经常编写yaml文件用于部署服务。

样例:

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[root@k8s-master ~]# vim pod-busybox.yaml
apiVersion: v1  # api版本
kind: Pod       # 资源类型
metadata:
  name: myapp-pod #名字
  labels:
    app: myapp # 标签内容
spec:
  containers:
  - name: myapp-container # 容器名
    image: busybox # 镜像名
    command: ['sh', '-c', 'echo Hello Kubernetes! && sleep 3600']

[root@k8s-master ~]# kubectl create -f pod-busybox.yaml 
pod/myapp-pod created
[root@k8s-master ~]# kubectl get pod
NAME        READY   STATUS              RESTARTS   AGE
myapp-pod   0/1     ContainerCreating   0          11s # 正在创建pod

[root@k8s-master ~]# kubectl get pod
NAME        READY   STATUS    RESTARTS   AGE
myapp-pod   1/1     Running   0          21s # 状态为Running
[root@k8s-master ~]#

配置文件详解

  • apiVersion: api版本，v1表示稳定版本，可以参考下面命令查看可用的版本
  • kind: 表示要创建的资源对象,关键字Pod ，可选关键字：Pod、ReplicaSet、ReplicationController、Deployment、StatefulSet、DaemonSet、Job、CronJob、HorizontalPodAutoscaling
  • metadata: 元数据，可以包含多个元数据
  • spec:表示资源对象的具体设置,containers表示容器的集合，可以定义多个容器

查看当前可用的API版本

Kubernetes 1.19.3

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[root@k8s-master ~]# kubectl api-versions
admissionregistration.k8s.io/v1
admissionregistration.k8s.io/v1beta1
apiextensions.k8s.io/v1
apiextensions.k8s.io/v1beta1
apiregistration.k8s.io/v1
apiregistration.k8s.io/v1beta1
apps/v1
authentication.k8s.io/v1
authentication.k8s.io/v1beta1
authorization.k8s.io/v1
authorization.k8s.io/v1beta1
autoscaling/v1
autoscaling/v2beta1
autoscaling/v2beta2
batch/v1
batch/v1beta1
certificates.k8s.io/v1
certificates.k8s.io/v1beta1
coordination.k8s.io/v1
coordination.k8s.io/v1beta1
discovery.k8s.io/v1beta1
events.k8s.io/v1
events.k8s.io/v1beta1
extensions/v1beta1
networking.k8s.io/v1
networking.k8s.io/v1beta1
node.k8s.io/v1beta1
policy/v1beta1
rbac.authorization.k8s.io/v1
rbac.authorization.k8s.io/v1beta1
scheduling.k8s.io/v1
scheduling.k8s.io/v1beta1
storage.k8s.io/v1
storage.k8s.io/v1beta1
v1

apiVersion该用哪一个，可以参考：https://www.jianshu.com/p/457cf0835f88

Pod yaml格式参考

使用 kubectl explain pods.spec.containers 命令获取参数

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[root@k8s-master ~]# kubectl explain pods.spec.containers
KIND:     Pod
VERSION:  v1

RESOURCE: containers <[]Object>

DESCRIPTION:
     List of containers belonging to the pod. Containers cannot currently be
     added or removed. There must be at least one container in a Pod. Cannot be
     updated.

     A single application container that you want to run within a pod.

FIELDS:
   args <[]string>
     Arguments to the entrypoint. The docker image's CMD is used if this is not
     provided. Variable references $(VAR_NAME) are expanded using the
     container's environment. If a variable cannot be resolved, the reference in
     the input string will be unchanged. The $(VAR_NAME) syntax can be escaped
     with a double $$, ie: $$(VAR_NAME). Escaped references will never be
     expanded, regardless of whether the variable exists or not. Cannot be
     updated. More info:
     https://kubernetes.io/docs/tasks/inject-data-application/define-command-argument-container/#running-a-command-in-a-shell

   command      <[]string>
     Entrypoint array. Not executed within a shell. The docker image's
     ENTRYPOINT is used if this is not provided. Variable references $(VAR_NAME)
     are expanded using the container's environment. If a variable cannot be
     resolved, the reference in the input string will be unchanged. The
     $(VAR_NAME) syntax can be escaped with a double $$, ie: $$(VAR_NAME).
     Escaped references will never be expanded, regardless of whether the
     variable exists or not. Cannot be updated. More info:
     https://kubernetes.io/docs/tasks/inject-data-application/define-command-argument-container/#running-a-command-in-a-shell

   env  <[]Object>
     List of environment variables to set in the container. Cannot be updated.

   envFrom      <[]Object>
     List of sources to populate environment variables in the container. The
     keys defined within a source must be a C_IDENTIFIER. All invalid keys will
     be reported as an event when the container is starting. When a key exists
     in multiple sources, the value associated with the last source will take
     precedence. Values defined by an Env with a duplicate key will take
     precedence. Cannot be updated.

   image        <string>
     Docker image name. More info:
     https://kubernetes.io/docs/concepts/containers/images This field is
     optional to allow higher level config management to default or override
     container images in workload controllers like Deployments and StatefulSets.
 ......

基本操作

查询所有正在运行的pod

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[root@k8s-master ~]# kubectl get pod
NAME        READY   STATUS    RESTARTS   AGE
myapp-pod   1/1     Running   0          21s

查询单个pod名，可以使用-w持续监听

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[root@k8s-master ~]# kubectl get pod myapp-pod
NAME        READY   STATUS    RESTARTS   AGE
myapp-pod   1/1     Running   0          21m

[root@k8s-master ~]# kubectl get pod -w
NAME        READY   STATUS    RESTARTS   AGE
myapp-pod   1/1     Running   0          24m

查询详情，可以查看调度到哪台主机上

kubectl get pod {pod 名} -o wide

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[root@k8s-master ~]# kubectl get pod myapp-pod -o wide
NAME        READY   STATUS    RESTARTS   AGE   IP           NODE        NOMINATED NODE   READINESS GATES
myapp-pod   1/1     Running   0          21m   10.244.2.6   k8s-node2   <none>           <none>
[root@k8s-master ~]#

查询pod输出的log

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[root@k8s-master ~]# kubectl logs myapp-pod
Hello Kubernetes!
[root@k8s-master ~]#

查询更加详细的pod数据

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[root@k8s-master ~]# kubectl describe pods myapp-pod
Name:         myapp-pod
Namespace:    default
Priority:     0
Node:         k8s-node2/172.19.153.99
Start Time:   Fri, 23 Oct 2020 14:45:32 +0800
Labels:       app=myapp
Annotations:  <none>
Status:       Running
IP:           10.244.2.6
IPs:
  IP:  10.244.2.6
Containers:
  myapp-container:
    Container ID:  docker://3075475b43e69240d392eec14f4fa67bfed524fedbb0f505c56d257ff916080f
    Image:         busybox
    Image ID:      docker-pullable://busybox@sha256:a9286defaba7b3a519d585ba0e37d0b2cbee74ebfe590960b0b1d6a5e97d1e1d
    Port:          <none>
    Host Port:     <none>
    Command:
      sh
      -c
      echo Hello Kubernetes! && sleep 3600
    State:          Running
      Started:      Fri, 23 Oct 2020 14:45:48 +0800
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-4dfgr (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             True 
  ContainersReady   True 
  PodScheduled      True 
Volumes:
  default-token-4dfgr:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-4dfgr
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
                 node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
  Type    Reason     Age   From               Message
  ----    ------     ----  ----               -------
  Normal  Scheduled  27m   default-scheduler  Successfully assigned default/myapp-pod to k8s-node2
  Normal  Pulling    27m   kubelet            Pulling image "busybox"
  Normal  Pulled     27m   kubelet            Successfully pulled image "busybox" in 16.092616692s
  Normal  Created    27m   kubelet            Created container myapp-container
  Normal  Started    27m   kubelet            Started container myapp-container

get命令支持json或者yaml的格式化输出

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[root@k8s-master ~]# kubectl get pod myapp-pod --output yaml
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: "2020-10-23T06:45:31Z"
  labels:
    app: myapp
  managedFields:
  - apiVersion: v1
    fieldsType: FieldsV1
  ..............................
        startedAt: "2020-10-23T06:45:48Z"
  hostIP: 172.19.153.99
  phase: Running
  podIP: 10.244.2.6
  podIPs:
  - ip: 10.244.2.6
  qosClass: BestEffort
  startTime: "2020-10-23T06:45:32Z"

参考